1. Field
The inventive concept relates to a distributed antenna system (DAS), and more particularly, to a downlink digital signal summation in a DAS.
2. Description of Related Art
A distributed antenna system (DAS) may have various topologies in consideration of particularity of its installation areas and application fields (e.g., in-building, subway, hospital, stadium, etc.). Moreover, in the DAS, a hub unit (HUB) may be introduced when it is difficult to install remote units (RUs) as many as a number required to be installed due to a limited number of branches of a main unit (MU).
According to a topology form, a plurality of MUs may be connected to a single HUB, and a plurality of RU may be connected in a star or cascade structure through the HUB. In this case, there is required a method in which, when different sub-band signals in the same service band are transmitted from each MU to the HUB, signals can be efficiently transmitted to the RUs posterior to the HUB.